ABSTRACT
Efforts to refine diagnostic approaches in all areas of psychiatry have assumed increasing importance over the past three decades. Subtypes within major disorders have been not only described but in several instances have demonstrated differing treatment responses and outcomes depending on subtype. Although such observations reinforce the importance of clearly delineated accurate diagnostic approaches, they also point toward different underlying pathophysiological/neurobiological mechanisms. Meaningful diagnosis must have some predictive value in grouping individuals who share certain signs and symptoms, have certain commonalties in how they manifest an illness, how their course of illness unfolds, what their family histories have in common, how they respond to treatment, and what their potential outcomes are. In view of their relatively favorable response to both psychotherapeutic and psychopharmacological treatments, the mood disorders have gained widespread attention with respect to identification of pertinent subtypes. For example, the observation that different subtypes of both bipolar and unipolar mood disorders respond to different treatment approaches underscores not only the importance of diagnosis but also the possibility that different subtypes might have differing psychobiological bases for their variable responses to treatment.
